In an attempt to reduce the amount of 'reinfented wheels' (esp. my own's)
I'm looking for some code (preferable with application notes for the circuits)
concering radio control and motor control - preferable with PICs (but no
exlusive):

1. Decoding the servo impulse/s from a RC receiver:
* preferable a 'self learning' application
* determination of multiple levels of modulation (centre, and max. would
certainly be of help for the beginning)
* 'fail save'-state whilste there is a signal loss/no signal

2. Controlling of a model motor (car/aeroplane):
* multiple steps of speed/fine control of revolutions
preferably PWM (pulse width modulation) with a high frequenzy
* acceleration/deceleration slope (programable)
* high currents of 50A (standard, with shorttime current of up to 100A)
* single/dual direction control
* motorbrake
* current sensing to detect shorts/blocking motor

I thing it's obvious that I'm trying to build a RC motor controller. Since I
know that many commercial products nowadays have a PIC (I know of 54 or 84)
inside, it should be possible to build such a thing.
my draft for such a device:
combination of the above (1., 2.)
PIC 16C84 (still the only one I can program) with information storage
in internal EEPROM (receiver impuls, slew rate, motor data)
modular final stage for cars or planes (brake, single/dual direction,
etc.)

Since there are so many (aren't there?) RC modellers on the list it would be
interesting to share informations/experiences on the subject of using PICs in
RC models (in the whole and motor controllers especially).

With the minimal research I have done so far I also encountered some questions:
* What is the best way to do multiple tasks with a PIC (esp. 16C84)?
Ex.: In a motor controller I would have to watch for the incomming impulses
whilst pulse width modulating a motor, sensing the current, etc.
To bad if I'm stuck in a wait loop... (If you know what I mean :-)
Since I want to use the 84 - How do I put the interrupts to best use?
* Which (power) transistors should I use in the final stage?
BUZ11 looks promissing.. but SIPMOS TEMPFETs/PROFETs/TOPFETs also look good
(though a much higher price, but temperature/shorts protection)
What would be the "best" transistor for my task ? (low Rds[on] <50mOhm,
Id[max] >20A, reasonable pricing/pice, etc.)

BTW: I bought some BUZ11 which have an 'A' mark on the cooling metal.
Does that mean that those FETs are in fact BUZ11As and not BUZ11s.
The plastic housing has printed 'BUZ11' on it (NO A) but what about
the mark on the metal... ???
What's the best way to measure the Rds[on] with hobbiest equipment
(some DVMs [not acurate in mOhms-Measuring], Scope [10MHz])?

Finaly you might ask yourself, why I don't buy one of those commercial juwels
(Ahh.. controllers)?
A. Inflexibility: ('Please define [in-]flex-i-bil-i-ty... Ahh')
Commercial controllers are trimmed for a single task. If I want to
control a model car and a model aeroplane I would have to buy two
controllers <cliiing>, although I wouldn't use both models at the same time.
It's allmost impossible to find a controller which is really adequat for the
given task. 'Testing a controller ? - Impossible - buy it first!' <cling>
I also want to control the slew rate ('Expensive... 8-]' <cling,cling>) of
the motor with my PC ('Impossible... :-(').

B. The Price: (Isn't it allways ?)
As I wrote above - RC motor controllers are sold at the price of juwels.
But a diamond wouldn't explode/burn out if you connect the power supply
the wrong way - And who didn't/doesn't make mistakes. Such controllers also
age at a rapid speed (Every year there is something new). If the nowadays
controller is damaged nobody but the manufactorer will repair it (time delay,
prohibitive cost). So it's off to the bank to get a new loan.

C. Experience:
I'm still very new to the PICs. I know it will be a hard way to a functinal
unit but I certainly will learn my share.
With the knowledge gained I could easily repair the RC motor controller :-)
Thus *no more garbage collection* for high tech stuff! ;-)
And ... 'What you know You KNOW.'

Use a "state" variable to control where you are in each task and execute
each task in turn via some time sharing scheme, e.g. 2ms for you, 5ms for
you and so on. To control time, you can setup a timer to count down to zero
and then generate an interrupt - set a flag and the current task will finish
what it's doing when the task checks this flag. Each critical input (such as
waveform period measurements) could generate interrupts on selected edges
and store these measurements for further processing in the appropriate task(s).

Just some thoughts ... hope it gives you some new ideas ...

>* Which (power) transistors should I use in the final stage?

I say, read the specifications and look at some examples in the data sheets.
Then try it out on a protoboard (maybe not 20A though).

To measure Rds[on] you can setup a test circuit with high power resistors
and try it out in practise. I did so when I started to build a mega led
display with over 1000 leds and controlled by the well-known Z80-processor.
(The project is currently on halt, I wonder why?)

-- chop --- chop --

>C. Experience:
> I'm still very new to the PICs. I know it will be a hard way to a functinal
> unit but I certainly will learn my share.

A small advice ... start with a simple project to learn the basics. I
started with the '54 and I was surprised how much code you actually could
fill it with.

>What kind of RC model needs 50 or 100 Amps of current? Even at 9-volts thats
>into the horsepower range!!!

The Kalt Whisper electric RC helicopter takes around 35 Amps (average), at
9.6 volts. It only flies for 6 minutes. People I've talked with say
performance just isn't comparable to gas motors. Maybe soon Zinc-air or some
other fuel-cell technology will make electric airplanes and helicopters a
bit more practical. The speed controller in the helicopter ad has 8 TO-220
power FET tabs protruding from its case.

>I'm looking for some code (preferable with application notes for the circuits)
>concering radio control and motor control - preferable with PICs (but no
>exlusive):
>
The Circuit Cellar BBS (860) 871-1988, has the file SERVOPIC.ZIP in File
Area 1 from the October 1994, Issue #51
magazine. You may be able to get it from their web site. The code is for PWM
multiple servo's.

>1. Decoding the servo impulse/s from a RC receiver:
> * preferable a 'self learning' application
> * determination of multiple levels of modulation (centre, and max. would
> certainly be of help for the beginning)
> * 'fail save'-state whilste there is a signal loss/no signal

It might be better to use PIC to modulate and demodulate your signal,
tapping the receiver's comparator output and your transmitters modulation
input. That way, you can employ error detection and correction codes in
firmware.

>* What is the best way to do multiple tasks with a PIC (esp. 16C84)?
> Ex.: In a motor controller I would have to watch for the incomming impulses
> whilst pulse width modulating a motor, sensing the current, etc.
> To bad if I'm stuck in a wait loop... (If you know what I mean :-)
> Since I want to use the 84 - How do I put the interrupts to best use?

Read Microchip's AP-Note AN-585 "A real-Time Operating System for PIC16/17".
Read about state-machine design in a textbook. The April 92 Computer
Applications Journal has a good article on state-machine design.

> What's the best way to measure the Rds[on] with hobbiest equipment
> (some DVMs [not acurate in mOhms-Measuring], Scope [10MHz])?

I would observe the voltage drop across the FET, motor and batteries in
operation. Then use the series current to determine where the power is going.

I'm interested in a good power FET too. I don't like high-side drives &
charge pumps.

Many of the high performance airplanes such as the sailplanes flown in
F5B competition and even larger sport models use 18-26 cells and draw
50 amps plus. Some of the F5B racers will drain a 20+ cell pack of 1700
mAh batteries in 20 seconds or so.

>I'm looking for some code (preferable with application notes for the circuits)
>concering radio control and motor control - preferable with PICs (but no
>exlusive):
>

I have built a small RX-FM receiver with synthetized frenquency for RC-model.
This receiver use RF and PLL MOTOROLA chip, for RF part and a PIC16C57 with
a small EEPROM to decode the RC signal. This circuit run in 2 meters glider
since 2 months - no crash !!! -
If you are interested in PIC code, schematic and PCB, I will be happy to post
you the whole document.
I 'm now developping a TX-FM synthetized tranceiver with LCD panel and a
8031.

>>I'm looking for some code (preferable with application notes for the circuits)
>>concering radio control and motor control - preferable with PICs (but no
>>exlusive):
>>
>
>I have built a small RX-FM receiver with synthetized frenquency for RC-model.
>This receiver use RF and PLL MOTOROLA chip, for RF part and a PIC16C57 with
>a small EEPROM to decode the RC signal. This circuit run in 2 meters glider
>since 2 months - no crash !!! -
>If you are interested in PIC code, schematic and PCB, I will be happy to post
>you the whole document.
>I 'm now developping a TX-FM synthetized tranceiver with LCD panel and a
>8031.
>
> Philippe TECHER at "@spam@sonyedeKILLspamiway.fr"
>

>
> I have built a small RX-FM receiver with synthetized frenquency for RC-model.
> This receiver use RF and PLL MOTOROLA chip, for RF part and a PIC16C57 with
> a small EEPROM to decode the RC signal. This circuit run in 2 meters glider
> since 2 months - no crash !!! -
> If you are interested in PIC code, schematic and PCB, I will be happy to post
> you the whole document.
> I 'm now developping a TX-FM synthetized tranceiver with LCD panel and a
> 8031.
>
> Philippe TECHER at "KILLspamsonyedeKILLspamiway.fr"
>

Hi, I am looking for just a link, I am currently modifing my son's toy
school bus with a motor and lights... I was looking at infrared to control
it. Perhaps what you have can also do the trick. Please EMAIl me the details
to RemoveMEdavidwTakeThisOuTggx.com.

>I have built a small RX-FM receiver with synthetized frenquency for RC-model.
>This receiver use RF and PLL MOTOROLA chip, for RF part and a PIC16C57 with
>a small EEPROM to decode the RC signal. This circuit run in 2 meters glider
>since 2 months - no crash !!! -
>If you are interested in PIC code, schematic and PCB, I will be happy to post
>you the whole document.
>I 'm now developping a TX-FM synthetized tranceiver with LCD panel and a
>8031.
>
> Philippe TECHER at "spamBeGonesonyedespamBeGoneiway.fr"
>